Arithmetical slate.



No. L275. Patented June 5, I900.

' H. C. SEILER I um Willi?? Y I nlllmmnmflm; i v I i "1 UNITED STATES PATENT Fries.

HARRY CLAUD SEILER, OF MILTON, PENNSYLVANIA, ASSIGNOR TO THE 1 MOUNT HOLLY STATIONERY AND PRINTING COMPANY, OF MOUNT HOLLY SPRINGS, PENNSYLVANIA. v

ARITHM EYTIQAAL SLATE.

SPECIFICATION forming part of Letters Patent No. 651,275, dated June 5 1900. Application filed October 12,1899; Serial No. 734,004. on model.)

To all whom it may concern:

Be it known that I, HARRY OnAUD SEILER,

residing at Milton, in, the county of Northumberland and State of Pennsylvania, have made certain new and useful Improvementsing in primary arithmetic, and the apparatus as shown embodies a board or slate whose surface is divided into two sections, one ofwhichhas a central sight-opening, while the other section has a sight-opening adjacent to a slate-surface on an intermediate cross-bar, and disks back of the slate and arranged to expose portions of their surfaces through their respective sight-openings, so figures on said disks may be brought successively into View through the sight-opening, so the problems in addition, multiplication, subtraction, and division can be quickly and accurately indicated.

The invention consists in certain novel constructions and combinations of parts, as will be hereinafter described, and pointed out in the claims. I

In the drawings, Figure l is a face View of a slate embodying my invention. Fig. 2 is a back View thereof, portions of the rear crossbars being broken away; and Fig. 3 is a detail cross-section on about line 3 3 of Fig. 2.

In carrying out my invention I employ a main frame A, in which is fitteda slate B. In the use of the term slate for defining the portion B of my device, as well as the disks presently described, I do not wish to be understood as limiting myself to the slate of commerce, as any of the ordinary substitutes having writing-surfaces may be used instead of the slate of commerce without departing from the principles of my invention.

The slate B has its front surface divided by the intermediate cross-bar G into sections D and E, the former constituting a square, as is best shown in Fig. 1. The intermediate cross-bar O is secured within the frame A and extends across the face of the slate B and is provided at C with a slate-surface, on which may be indicated any of the arithmetical marks, such as as'shown in Fig. 1, or as may be desired. I

The slate is provided centrally of its square D with a sight-opening D, and a similar sight-opening E is provided in the section E adjacent to the slate-surface C, so the figure exposed throughthe opening E may be conveniently read in connection with the arithmetical mark produced 011 the slate-surface O.

In rear of the slate B, I provide the bearingbars F and G, which are secured to the frame, extend across in rear of the slate, and are spaced from the latter sufficiently to permit the application of the disks and pulleys between said slate and the bearing-bars. Disks 'H and I are journaled by means of shafts H and I, on which they turn and are arranged to expose their surfaces near their peripheries through their respective sight-openings D and E, so the figures produced in series on the disks H and I may beexposed as de sired through the sight-openings. In order to conveniently turn the disks H and I, I provide gearing consisting of pulleys H and I whichare secured to the disks H and I and are geared by belts H and I with pulleys J and K on shafts J and K, which shafts have handles J and K in the form of knobs and arranged in front of the slate and close together for convenience of operation. The shafts J and K are journaled in the slate and the back bearing-bar G and project in front of the slate to receive the knobs before described.

On the slate I usually pr0vide,'by chalk or otherwise, a series of figures forming a square around the central'opening D and provide.

figures on the disks H and I, which may be brought into View through their respective sight-openings, as maybe desired. The numbersfrom 1 to 12 are preferably fixed permanently on the disk H and are to be used as subtrahends, multipliers, and divisors. The disk II is revolved at the option of the teacher by the small knob, and the numbers may be placed by a crayon in any order around the opening D. The teacher with a pointer drills his pupils by pointing to the number in the square and placing it immediately in use with the figure that shows through the opening D. The disk I, also provided with numbers l to 12, may be used for drill and practical work in connection with the other portion of the board.

If in practice the teacher is instructing in addition, the fifth table is indicated by the central opening D, and he places his pointer on the figure 1 in the square, thus indicating the addition of five and one. The pointer may then be placed on the next or any other figure, and so on, thus avoiding the sing-song work commonly employed.

Addition, subtraction, and division can be taught in connection with multiplication by using the numbers on the right-hand disk, thus: Five times six are thirty plus three are thirty-three, or thirty minus three are twentyseven, or thirty divided by three are ten. Division can be taught separately byplacing large numbers in the square and using the center number as a divisor. By using the disk I exercises in addition, subtraction, and multiplication can be had inconnection with division.

Having thus described my invention, What, I claim, and desire to secure by Letters Patout, is o 1. An apparatus substantially as described, comprising the main frame, the slate therein provided with sight-openings spaced apart, the intermediate bar secured to the main frame and crossing the slate between its sight openings and provided with a slate-surface for the arithmetical marks such as (plus) and (minus), the bearing-bars extended across the main frame in rear of the slate and spaced apart from said slate, such bearingbars being arranged in lines on opposite sides of the intermediate front bar, the disks lying between the slate and their respective bearing-bars and having their shafts supported in said slate and bars, the pulleys in connection with said disks, the disks being arranged to be seen at points near their peripheries through their respective sight-openings, the drive-shafts having pulleys and operatinghandles, and gearing connecting said pulleys with the pulleys of their respective disks substantially as set forth.

2. An apparatus substantially as described comprising the slate-frame, the slate, the intermediate cross-bar having a blackboard-surface and dividing the slate into sections having sight-openings in each section, and the disks in rear of the slate and arranged for exposure through their respective sight-openings substantially as set forth.

3. An apparatus substantially as described comprising a slate-frame, the slate therein having sight-openings spaced apart, bearingbars in rear of the slate and spaced apart therefrom, and the disks arranged between said bearing-bars and the slate and arranged to expose portions of their surfaces through the sight-openings in the slate and the pulleys and gearing for operating said diskssubstantially as set forth.

HARRY OLAUD SEILER.

Witnesses:

THos. SWENK, Jr., H. E. ANGSTADT. 

